1 files changed, 138 insertions, 23 deletions

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 9a7def7c3237..5e75944ad5d1 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -19,6 +19,7 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/spi-mem.h>
 #include <linux/of_gpio.h>
+#include <linux/gpio/consumer.h>
 #include <linux/pm_runtime.h>
 #include <linux/pm_domain.h>
 #include <linux/property.h>
@@ -35,6 +36,8 @@
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/spi.h>
+EXPORT_TRACEPOINT_SYMBOL(spi_transfer_start);
+EXPORT_TRACEPOINT_SYMBOL(spi_transfer_stop);
 
 #include "internals.h"
 
@@ -578,7 +581,10 @@ int spi_add_device(struct spi_device *spi)
 		goto done;
 	}
 
-	if (ctlr->cs_gpios)
+	/* Descriptors take precedence */
+	if (ctlr->cs_gpiods)
+		spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
+	else if (ctlr->cs_gpios)
 		spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];
 
 	/* Drivers may modify this initial i/o setup, but will
@@ -772,10 +778,21 @@ static void spi_set_cs(struct spi_device *spi, bool enable)
 	if (spi->mode & SPI_CS_HIGH)
 		enable = !enable;
 
-	if (gpio_is_valid(spi->cs_gpio)) {
-		/* Honour the SPI_NO_CS flag */
-		if (!(spi->mode & SPI_NO_CS))
-			gpio_set_value(spi->cs_gpio, !enable);
+	if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) {
+		/*
+		 * Honour the SPI_NO_CS flag and invert the enable line, as
+		 * active low is default for SPI. Execution paths that handle
+		 * polarity inversion in gpiolib (such as device tree) will
+		 * enforce active high using the SPI_CS_HIGH resulting in a
+		 * double inversion through the code above.
+		 */
+		if (!(spi->mode & SPI_NO_CS)) {
+			if (spi->cs_gpiod)
+				gpiod_set_value_cansleep(spi->cs_gpiod,
+							 !enable);
+			else
+				gpio_set_value_cansleep(spi->cs_gpio, !enable);
+		}
 		/* Some SPI masters need both GPIO CS & slave_select */
 		if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
 		    spi->controller->set_cs)
@@ -1024,6 +1041,8 @@ static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
 		if (max_tx || max_rx) {
 			list_for_each_entry(xfer, &msg->transfers,
 					    transfer_list) {
+				if (!xfer->len)
+					continue;
 				if (!xfer->tx_buf)
 					xfer->tx_buf = ctlr->dummy_tx;
 				if (!xfer->rx_buf)
@@ -1162,10 +1181,10 @@ out:
 	if (msg->status && ctlr->handle_err)
 		ctlr->handle_err(ctlr, msg);
 
-	spi_res_release(ctlr, msg);
-
 	spi_finalize_current_message(ctlr);
 
+	spi_res_release(ctlr, msg);
+
 	return ret;
 }
 
@@ -1615,13 +1634,21 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 		spi->mode |= SPI_CPHA;
 	if (of_property_read_bool(nc, "spi-cpol"))
 		spi->mode |= SPI_CPOL;
-	if (of_property_read_bool(nc, "spi-cs-high"))
-		spi->mode |= SPI_CS_HIGH;
 	if (of_property_read_bool(nc, "spi-3wire"))
 		spi->mode |= SPI_3WIRE;
 	if (of_property_read_bool(nc, "spi-lsb-first"))
 		spi->mode |= SPI_LSB_FIRST;
 
+	/*
+	 * For descriptors associated with the device, polarity inversion is
+	 * handled in the gpiolib, so all chip selects are "active high" in
+	 * the logical sense, the gpiolib will invert the line if need be.
+	 */
+	if (ctlr->use_gpio_descriptors)
+		spi->mode |= SPI_CS_HIGH;
+	else if (of_property_read_bool(nc, "spi-cs-high"))
+		spi->mode |= SPI_CS_HIGH;
+
 	/* Device DUAL/QUAD mode */
 	if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
 		switch (value) {
@@ -2137,6 +2164,62 @@ static int of_spi_register_master(struct spi_controller *ctlr)
 }
 #endif
 
+/**
+ * spi_get_gpio_descs() - grab chip select GPIOs for the master
+ * @ctlr: The SPI master to grab GPIO descriptors for
+ */
+static int spi_get_gpio_descs(struct spi_controller *ctlr)
+{
+	int nb, i;
+	struct gpio_desc **cs;
+	struct device *dev = &ctlr->dev;
+
+	nb = gpiod_count(dev, "cs");
+	ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
+
+	/* No GPIOs at all is fine, else return the error */
+	if (nb == 0 || nb == -ENOENT)
+		return 0;
+	else if (nb < 0)
+		return nb;
+
+	cs = devm_kcalloc(dev, ctlr->num_chipselect, sizeof(*cs),
+			  GFP_KERNEL);
+	if (!cs)
+		return -ENOMEM;
+	ctlr->cs_gpiods = cs;
+
+	for (i = 0; i < nb; i++) {
+		/*
+		 * Most chipselects are active low, the inverted
+		 * semantics are handled by special quirks in gpiolib,
+		 * so initializing them GPIOD_OUT_LOW here means
+		 * "unasserted", in most cases this will drive the physical
+		 * line high.
+		 */
+		cs[i] = devm_gpiod_get_index_optional(dev, "cs", i,
+						      GPIOD_OUT_LOW);
+		if (IS_ERR(cs[i]))
+			return PTR_ERR(cs[i]);
+
+		if (cs[i]) {
+			/*
+			 * If we find a CS GPIO, name it after the device and
+			 * chip select line.
+			 */
+			char *gpioname;
+
+			gpioname = devm_kasprintf(dev, GFP_KERNEL, "%s CS%d",
+						  dev_name(dev), i);
+			if (!gpioname)
+				return -ENOMEM;
+			gpiod_set_consumer_name(cs[i], gpioname);
+		}
+	}
+
+	return 0;
+}
+
 static int spi_controller_check_ops(struct spi_controller *ctlr)
 {
 	/*
@@ -2184,7 +2267,7 @@ int spi_register_controller(struct spi_controller *ctlr)
 {
 	struct device		*dev = ctlr->dev.parent;
 	struct boardinfo	*bi;
-	int			status = -ENODEV;
+	int			status;
 	int			id, first_dynamic;
 
 	if (!dev)
@@ -2198,12 +2281,6 @@ int spi_register_controller(struct spi_controller *ctlr)
 	if (status)
 		return status;
 
-	if (!spi_controller_is_slave(ctlr)) {
-		status = of_spi_register_master(ctlr);
-		if (status)
-			return status;
-	}
-
 	/* even if it's just one always-selected device, there must
 	 * be at least one chipselect
 	 */
@@ -2260,6 +2337,25 @@ int spi_register_controller(struct spi_controller *ctlr)
 	 * registration fails if the bus ID is in use.
 	 */
 	dev_set_name(&ctlr->dev, "spi%u", ctlr->bus_num);
+
+	if (!spi_controller_is_slave(ctlr)) {
+		if (ctlr->use_gpio_descriptors) {
+			status = spi_get_gpio_descs(ctlr);
+			if (status)
+				return status;
+			/*
+			 * A controller using GPIO descriptors always
+			 * supports SPI_CS_HIGH if need be.
+			 */
+			ctlr->mode_bits |= SPI_CS_HIGH;
+		} else {
+			/* Legacy code path for GPIOs from DT */
+			status = of_spi_register_master(ctlr);
+			if (status)
+				return status;
+		}
+	}
+
 	status = device_add(&ctlr->dev);
 	if (status < 0) {
 		/* free bus id */
@@ -2692,11 +2788,6 @@ static int __spi_split_transfer_maxsize(struct spi_controller *ctlr,
 	size_t offset;
 	size_t count, i;
 
-	/* warn once about this fact that we are splitting a transfer */
-	dev_warn_once(&msg->spi->dev,
-		      "spi_transfer of length %i exceed max length of %zu - needed to split transfers\n",
-		      xfer->len, maxsize);
-
 	/* calculate how many we have to replace */
 	count = DIV_ROUND_UP(xfer->len, maxsize);
 
@@ -2854,6 +2945,11 @@ int spi_setup(struct spi_device *spi)
 	 * so it is ignored here.
 	 */
 	bad_bits = spi->mode & ~(spi->controller->mode_bits | SPI_CS_WORD);
+	/* nothing prevents from working with active-high CS in case if it
+	 * is driven by GPIO.
+	 */
+	if (gpio_is_valid(spi->cs_gpio))
+		bad_bits &= ~SPI_CS_HIGH;
 	ugly_bits = bad_bits &
 		    (SPI_TX_DUAL | SPI_TX_QUAD | SPI_TX_OCTAL |
 		     SPI_RX_DUAL | SPI_RX_QUAD | SPI_RX_OCTAL);
@@ -2899,6 +2995,21 @@ int spi_setup(struct spi_device *spi)
 }
 EXPORT_SYMBOL_GPL(spi_setup);
 
+/**
+ * spi_set_cs_timing - configure CS setup, hold, and inactive delays
+ * @spi: the device that requires specific CS timing configuration
+ * @setup: CS setup time in terms of clock count
+ * @hold: CS hold time in terms of clock count
+ * @inactive_dly: CS inactive delay between transfers in terms of clock count
+ */
+void spi_set_cs_timing(struct spi_device *spi, u8 setup, u8 hold,
+		       u8 inactive_dly)
+{
+	if (spi->controller->set_cs_timing)
+		spi->controller->set_cs_timing(spi, setup, hold, inactive_dly);
+}
+EXPORT_SYMBOL_GPL(spi_set_cs_timing);
+
 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 {
 	struct spi_controller *ctlr = spi->controller;
@@ -2915,6 +3026,7 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 	 * cs_change is set for each transfer.
 	 */
 	if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
+					  spi->cs_gpiod ||
 					  gpio_is_valid(spi->cs_gpio))) {
 		size_t maxsize;
 		int ret;
@@ -2961,6 +3073,8 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 	 * it is not set for this transfer.
 	 * Set transfer tx_nbits and rx_nbits as single transfer default
 	 * (SPI_NBITS_SINGLE) if it is not set for this transfer.
+	 * Ensure transfer word_delay is at least as long as that required by
+	 * device itself.
 	 */
 	message->frame_length = 0;
 	list_for_each_entry(xfer, &message->transfers, transfer_list) {
@@ -2970,8 +3084,6 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 
 		if (!xfer->speed_hz)
 			xfer->speed_hz = spi->max_speed_hz;
-		if (!xfer->speed_hz)
-			xfer->speed_hz = ctlr->max_speed_hz;
 
 		if (ctlr->max_speed_hz && xfer->speed_hz > ctlr->max_speed_hz)
 			xfer->speed_hz = ctlr->max_speed_hz;
@@ -3031,6 +3143,9 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 				!(spi->mode & SPI_RX_QUAD))
 				return -EINVAL;
 		}
+
+		if (xfer->word_delay_usecs < spi->word_delay_usecs)
+			xfer->word_delay_usecs = spi->word_delay_usecs;
 	}
 
 	message->status = -EINPROGRESS;